Digital telecommunication systems are currently evolving from the so-called first generation of narrow band networks, which are primarily directed to the handling of voice and data traffic, to a new generation of broad band networks which can carry a full range of multimedia services. Within a typical narrow band network, traffic and control information are carried in 64 kbit/s bearer channels using time division multiplexing (TDM). Routing to establish communications channels between end users is determined by the network nodes each of which is provided with a set of routing tables so as to set up an optimum route for each communication. The new broad band networks however are asynchronous in nature and carry traffic in the form of packets of cells each of which incorporates a header containing information whereby the packet is routed by the asynchronous switching fabric. Thus, if narrow band network traffic is to be carried over a broad band network, there is a problem of interfacing the narrow band circuit switched environment with the broad band packet environment. Further, there are differences in signalling protocols between the two types of network, and there is thus a need for a mechanism for carrying the narrow band signalling traffic over the broad band network such that the narrow band signalling remains fully functional.
It will be appreciated that there is currently a large investment in narrow band network systems and there is thus a requirement for interworking between the two types of network such that narrow band traffic can be transported over a broad band network so as to provide end to end connectivity between narrow band network terminals. To achieve this interworking, it is necessary to adapt the narrow band traffic for transmission over the broad band network and to ensure that the narrow band signalling messages are accommodated.
Our co-pending application Ser. No. 08-907521 entitled "System and method for establishing a communication connection" describes an arrangement and method in which a connection broker acts as a single point of contact for the provision of connection services to a call server in a telecommunications network and orchestrates interconnection of first and second narrow band networks. Every request relating to a connection involving any link on the node is constrained to pass through this single entity. This arrangement provides an effective method of interconnecting the narrow band networks. However, we have found that, under conditions of heavy traffic demand, the performance and scale of the node can be limited by the ability of the connection broker to handle all the interactions with the call server. In particular the speed with which a connection may be established and the number of connection requests that may be handled simultaneously are both limited to what can be achieved by a single, monolithic connection broker. Furthermore, as the connection broker represents a single critical item failure of which completely prevents the node from performing its function of establishing communication connections, it is desirable to provide a standby device that can be switched in to service in the event of a failure.